Stereochemical studies-XXXIII.1 1 Part XXXII, L. Gera, By. Göndös and G. Bernáth, Acta Chim. (Budapest) in press. Saturated heterocycles-IX2 2 Part VIII, Gy. Göndös, K.L. Láng, A. Szeghy, Gy. Dombi and G. Bernáth, J. Chem. Soc. Perkin I. Paper No. 8/971, accepted for publication.

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Abstract

Title full: Stereochemical studies-XXXIII.1 1 Part XXXII, L. Gera, By.Göndös and G. Bernáth, Acta Chim. (Budapest) in press. Saturated heterocycles-IX2 2 Part VIII, Gy. Göndös, K.L. Láng, A. Szeghy, Gy. Dombi and G. Bernáth, J. Chem. Soc. Perkin I. Paper No. 8/971, accepted for publication. Synthesis and conformations of stereoisomeric cis- and troans-tetramethylene- and pentamethylenedihydro-1,3-oxazines. By the reaction of cis- and trans-2-aminomethylcyclohexanol (1, 2), cis- and trans-2-hydroxymethyl-cyclohexylamine (3,4) and the homologous cycloheptane derivatives (5-8) with ethyl p-chlorobenzimidate (11), cis- and trans-5,6-tetramethylene- and pentamethylene-2,3,5,6-tetrahydro-4H-1,3-oxazines (12,13,16,17) and cis- and trans-4,5-tetramethylene- and pentaimethylene-4,5-dihydro-6H-1,3-oxazines (14, 15, 18, 19) were prepared. The amidine intermediate of the ring-closure reaction was isolated, and the mechanism of the acid-catalysed reaction is discussed. It follows from the 1H NMR data that in the preferred conformations of the cis-tetramethylene-tetrahydrooxazines the methylene group of the hetero ring is equatorial and the hetero atom (O or N) axial. In contrast, the conformation equilibria of the cis pentamethylene derivatives, in accordance with earlier X-ray analysis, are shifted towards the conformer containing the methylene group in isoclinal and the hetero atom in equatorial position. The preferred conformations 12a and 14a of the tetramethylene derivatives 12 and 14 were also determined by X-ray crystal analysis.

Original languageEnglish
Pages (from-to)799-807
Number of pages9
JournalTetrahedron
Volume35
Issue number6
DOIs
Publication statusPublished - 1979

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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